Reversible acetylation of core histones may play an important role in global transcriptional regulation in eucaryotic cells. Increased histone acetylation has been correlated with increased transcription (Roth et al. (1996) Cell 87:5-8) and conversely, studies suggest that deacteylation is correlated with transcriptional repression (Pazin et. al. (1997) Cell 89:325-328). A proposed mechanism of transcriptional regulation by histone deacetylation may involve a histone deacetylase that is linked (via protein-protein interactions) to a sequence specific DNA-bound repressor protein. Transcription repression occurs upon deacetylation of core histone proteins (Pazin et. al. (1997) Cell 89:325-328). Precisely how reversible acetylation of core proteins in turn controls gene expression is unknown however, several mechanisms for the regulation of transcription via core acetylation have been proposed by Pazine et al. One model suggests acetylation of histone lysine residues increases the access of transcription factors to the DNA. Another, suggests that acetylation of a lysine residue in a chromatin associated protein (histone or nonhistone) of a provides a signal that is recognized by another factor. Accordingly, the availability of nucleic acid sequences encoding all or a portion of histone deacetylase proteins would facilitate studies to better understand global transcriptional regulation in eucaryotic cells. It would also provide genetic tools for the manipulation of histone deacetylase activity and provide mechanisms to control transcriptional gene regulation in plants.
Several histone deacetylase proteins from corn, rice, soybean and wheat have been discovered. In the process of characterizing these proteins it was discovered that the histone deacetylase proteins had significantly different amino acid sequences, which suggested that these proteins constute a large family of chromatin associated deacetylase proteins. Several classes of histone deacetylase proteins were characterized (genes 1-4) by sets of conserved amino acid motifs and overall sequence homology. Specific conserved sequence motifs were consistent for each of the protein classes across species.